1. Field of the Invention
The present invention relates to the preparation of polymers from the polymerization of alpha, beta-ethylenically unsaturated monomers via aqueous latex polymerization techniques. More particularly, this invention relates to the aqueous latex polymerization of alpha, beta-ethylenically unsaturated monomers which includes at least one gaseous monomer.
2. Brief Description of the Prior Art
The polymerization of alpha, beta-ethylenically unsaturated monomers via aqueous latex polymerization techniques is well known in the art. The polymerization is conducted in aqueous medium in the presence of an emulsifying agent which may be a low molecular weight material such as a low molecular weight anionic material, for example, the alkali metal or ammonium salt of sulfates of alcohols having from 8 to 18 carbon atoms, specifically, sodium lauryl sulfate. Polymerization can also be conducted in the presence of a polymeric surfactant such as an anionic polymer, for example, an ammonia or amine-neutralized carboxylic acid group-containing acrylic polymer. This is shown, for example, in U.S. Pat. No. 4,064,087 to Das and U.S. Pat. No. 4,151,143 to Blank.
Among the polymerizable alpha, beta-ethylenically unsaturated monomers which may be polymerized are, of course, the normally liquid monomers such as the alkyl esters of acrylic and methacrylic acid, for example, methyl methacrylate and butyl acrylate; vinyl aromatic compounds such as styrene and vinyl toluene; and other assorted vinyl monomers such as vinyl acetate and acrylonitrile which polymerize quite readily. Gaseous monomers such as vinyl chloride and ethylene are difficult to polymerize via aqueous emulsion polymerization techniques. The monomers are added incrementally to the polymerizing reaction mixture and the monomer addition and reaction times are long because of excessive pressure build-up in the reactor. In this instance, the rate of gaseous monomer addition must be reduced or even stopped until the monomers polymerize and the pressure drops.
It is an object of the present invention to provide a method of polymerization of gaseous alpha, beta-ethylenically unsaturated monomers via aqueous latex polymerization techniques in a fast and economic manner.